1,2,4-Triazole derivatives

ABSTRACT

1,2,4-Triazole derivatives of the formula ##STR1## in which R 1  denotes methyl or optionally substituted phenyl, 
     R 2  denotes R 3  O-- in which R 3  is optionally substituted alkyl, alkinyl preferably having up to 3 carbon atoms, optionally substituted cycloalkyl, optionally substituted phenyl, or 
     R 2  denotes ##STR2##  in which R 4  is hydrogen or optionally substituted (C 1  -C 4 ) alkyl and R 5  is (C 1  -C 4 )alkyl or optionally substituted phenyl 
     are effective as fungicides and growth regulators.

This invention relates to novel 1,2,4-triazole derivatives, to their manufacture and their use as pesticides in plant protection and as agents for the regulation of growths of plants.

The compounds according to the invention have the formula I ##STR3## in which R₁ denotes methyl or phenyl optionally substituted by halogen, (C₁ -C₄)alkyl, preferably (C₁ -C₂)alkyl, or (C₁ -C₄)alkoxy, preferably (C₁ -C₂)alkoxy and

R₂ denotes the group R₃ O-- in which R₃ is alkyl, preferably having up to 12 carbon atoms and more preferably up to 8 carbon atoms, which may be substituted additionally by halogen, preferably chlorine or bromine, (C₁ -C₄)alkoxy or alkoxycarbonyl preferably having up to 8 carbon atoms, more preferably up to 5 carbon atoms; or is alkinyl preferably having up to 3 carbon atoms; or is cycloalkyl preferably having up to 6 carbon atoms and optionally substituted additionally by (C₁ -C₄)alkyl; or is phenyl optionally substituted by halogen or F₃ C--, or

R₂ denotes ##STR4## in which R₄ is hydrogen or (C₁ -C₄)alkyl optionally substituted by alkoxycarbonyl preferably having up to 8 carbon atoms, more preferably up to 5 carbon atoms and R₅ is (C₁ -C₄)alkyl or phenyl optionally substituted by halogen, F₃ C--, (C₁ -C₄)alkyl, (C₁ -C₄)alkoxy, phenoxy or halophenoxy.

In general, the compounds of formula I are obtained in the form of mixtures of cis/trans isomers which can be separated into the individual isomers by known methods.

The triazole derivatives of formula I can be produced by reacting a compound of the formula II ##STR5## in which R₁ and R₂ are as defined under formula I and Hal is chlorine or bromine, preferably chlorine, at elevated temperature, preferably of from 70° to 140° C. and more preferably 80° to 110° C., with 1,2,4-triazole in the presence of an agent binding hydrogen halide. The reaction is preferably carried out in an organic solvent, for example acetone, acetonitrile, dimethyl formamide or higher boiling hydrocarbons, for example xylene. To bind the hydrohalic acid formed in the reaction it proved advantageous to use an at least molar excess of the triazole or a corresponding amount of an inorganic or tertiary organic base, for example K₂ CO₃, Na₂ CO₃, triethylamine, pyridine or N,N-dimethylaniline.

The starting compounds of formula II which, for the most part, are also novel, can be produced in known manner from acid chlorides of the formula III ##STR6## by reaction with alcohols of the formula R₂ OH or amines of the formula ##STR7## in which formulae R₁, R₂, R₄, R₅ and Hal are as defined under formulae I and II.

The carboxylic acid chlorides of formula III can be produced by processes known from literature, for example by reacting a β-keto ester of the formula R₁ --CO--CH₂ --COOR with a chlorination agent (cf. JACS 77, 1137 (1955); J. Chem. Soc. 99, page 1621 (1911)).

The compounds of formula I are distinguished by a very good fungicidal effect. They can be used to combat curatively fungi that have already penetrated into the vegetal tissue. This is especially important and advantageous with fungal diseases which can no longer be combated with the usual fungicides once the infection has started. The compounds of the invention are effective, for example, against Phytophthora infestans, Plasmopara viticola, Venturia inaequalis, Cercospora betae and Tilletia tritici and above all, against types of genuine mildew in the cultivation of fruit, vegetable, cereals and vine and in horticulture. In part, they are also effective against rust fungi. It should be noted that the compounds of the invention have an outstanding effect against types of mildew that are resistant to benzimidazole derivatives, for example Benomyl and Carbendazim.

The compounds of formula I according to the invention can also be used in the technical field, for example in wood protecting agents, for paints, as preservatives, for example in lubricating cooling liquids for shaving metal. Moreover, some of the compounds exhibit a good effect against phytopathogeneous bacteria, the control of which increases in importance in horticulture and agriculture.

In biological experiments the compounds of formula I according to the invention exhibit very good growth regulating properties in a series of economically important plants. It should be noted especially that besides a general growth regulating effect, the compounds have a good growth inhibiting effect in cereals.

It has been proposed to regulate the growth of higher plants by the application of succinic acid 2,2-dimethylhydrazide, 2-chloroethyltrimethylammonium chloride and maleic acid hydrazide. The effect of these compounds is, however, not always satisfactory, for example, in that higher concentrations partially cause phytotoxic damages, the known compounds are ineffective in some important crop plants or the crop yield is impaired. In contradistinction thereto, the compounds of formula I according to the invention surprisingly exhibit an outstanding regulatory effect without phytotoxic damages occurring.

In plant protection the compounds of formula I can be used in the form of the usual formulations such as dusts, wettable powders, seed treating agents, dispersions, solutions, or emulsion concentrates. In general, the formulations contain from 2 to 95%, preferably 10 to 90% by weight of active compound of formula I. In addition, the formulations may contain the usual adhesives, wetting agents, dispersing agents, emulsifiers, penetration agents, solvents, fillers and carriers.

The following examples illustrate the invention.

(A) EXAMPLES OF PREPARATION

EXAMPLE 1 3-(1,2,4-Triazol-1-yl)-cinnamic acid-N-isopropyl-2',6'-dimethyl anilide ##STR8##

0.07 Mol (22.9 g) of 3-chloro-cinnamic acid N-isopropyl-2',6'-dimethyl anilide were dissolved in 90 ml of dimethyl formamide, 5.8 g (0.084 mol) of 1,2,4-triazole and 11.5 g of anhydrous potassium carbonate were added and the whole was kept for 6 hours at 100° C. while stirring. After cooling of the reaction mixture and pouring into iced water, it was extracted with methylene chloride and the organic phase was washed with water. After removal of the methylene chloride under reduced pressure, 23.6 g of an amber-colored, semicrystalline product were obtained which, according to thin layer chromatography, consisted of approximately equal parts of cis- and trans-isomer of 3-(1,2,4-triazol-1-yl)-cinnamic acid N-isopropyl-2',6'-dimethyl anilide.

Yield 23.6 g=93.5% of the theory. Thin layer chromatogram: R_(f) 0.4 and 0.5. (pre-fabricated plates of silica gel 60 F₂₅₄ of Messrs. Merck). eluent: ethyl acetate. Analysis: C₂₂ H₂₄ N₄ O; MW 360.4. calculated C 73.30%; H 6.71%; N 15.54%. found C 73.2%; H 6.7%; N 15.5%.

After recrystallization of a sample of toluene/gasoline, colorless crystals melting at 160° to 161° C. and having correct analytical values were obtained. NMR spectrum and thin layer chromatogram indicated a strong enrichment of one of the two isomers.

EXAMPLE 2 3-(1,2,4-Triazol-1-yl)-4'-chloro-cinnamic acid isobutyl ester ##STR9##

0.07 Mol (19.1 g) of 3-chloro-4'-chlorocinnamic acid isobutyl ester was reacted with 1,2,4-triazole under the conditions of Example 1. After working up, a honeycolored viscous sirup was obtained which, according to thin layer chromatography (eluent toluene/ethyl acetate 2:1); R_(f) values 0.38 and 0.45 consisted of a mixture of cis- and trans-isomers of 3-(1,2,4-triazol-1-yl)-4'-chlorocinnamic acid isobutyl ester.

Yield 19.5 g=91% of the theory. Analysis: C₁₅ H₁₆ ClN₃ O₂ ; MW 305.7. calculated C 58.92%; H 5.27%; N 13.74%. found C 58.6%; H 5.0% N 13.5%.

EXAMPLE 3 3-(1,2,4-Triazol-1-yl)-crotonic acid isobutyl ester ##STR10##

0.1 Mol (17.7 g) of 3-chlorocrotonic acid isobutyl ester in 100 ml acetonitrile, 012 mol (8.3 g) of 1,2,4-triazole and 0.12 mol (16.5 g) of anhydrous potassium carbonate were refluxed for 5 hours. After removal of the solvent under reduced presure, the reaction mixture was cooled, water was added and the resulting mixture was extracted with methylene chloride. After distillation of the methylene chloride under reduced pressure, the 3-(1,2,4-triazol-1-yl)-crotonic acid isobutyl ester was obtained in the form of a weakly yellow oil.

Yield 18.2 g=87% of the theory. Thin layer chromatogram (toluene/ethyl acetate 2:1). R_(f) 0.2. Analysis: C₁₀ H₁₅ N₃ O₂ ; MW 209.2. calculated C 57.40%; H 7.23%; N 20.08%. found C 57.1%; H 7.3%; N 19.8%.

EXAMPLES 4 to 90

Examples 4 to 6 were carried out in the manner described in Example 3 while Examples 7 to 90 were carried out under the conditions of Example 1. In the following table are indicated the radicals R₁ and R₂ of the compounds prepared from corresponding compounds of formula II and the melting points or the refractive index of said compounds.

                                      TABLE 1                                      __________________________________________________________________________      ##STR11##                             formula I                               Example                                                                        No.  R.sub.1  R.sub.2        m.p. (°C.)                                 __________________________________________________________________________     4    CH.sub.3                                                                                 ##STR12##     106-107                                           5    CH.sub.3 (CH.sub.3).sub.2 CHO                                                                          42-44                                                                          0.3/105                                           6    CH.sub.3 CH.sub.3 (CH.sub.2).sub.3 O                                                                   oil                                                     ##STR13##                                                                              CH.sub.3 O     74-88                                             8                                                                                    ##STR14##                                                                              C.sub.2 H.sub.5 O                                                                             oil                                               9                                                                                    ##STR15##                                                                              (CH.sub.3).sub.2 CHO                                                                          0,3/147                                           10                                                                                   ##STR16##                                                                              CH.sub.3 CH.sub.2 CH.sub.2 O                                                                  oil                                               11                                                                                   ##STR17##                                                                              (CH.sub.3).sub.2 CHCH.sub.2 O                                                                 oil                                               12                                                                                   ##STR18##                                                                              CH.sub.3 (CH.sub.2).sub. 3 O                                                                  oil                                               13                                                                                   ##STR19##                                                                              (CH.sub.3).sub.3 CO                                                                           semi- crystalline                                 14                                                                                   ##STR20##                                                                               ##STR21##     oil                                               15                                                                                   ##STR22##                                                                               ##STR23##     oil                                               16                                                                                   ##STR24##                                                                              CHCCH.sub.2 O  oil                                               17                                                                                   ##STR25##                                                                               ##STR26##     99-115                                            18                                                                                   ##STR27##                                                                               ##STR28##     108-121 (138-140).sup.(+)                         19                                                                                   ##STR29##                                                                              N(C.sub.2 H.sub.5).sub.2                                                                      oil                                               20                                                                                   ##STR30##                                                                              N(CH.sub.2 CH.sub.2 CH.sub.3).sub.2                                                           oil                                               21                                                                                   ##STR31##                                                                              N[CH(CH.sub.3).sub.2 ].sub.2                                                                  150-151                                           22                                                                                   ##STR32##                                                                               ##STR33##     160-162                                           23                                                                                   ##STR34##                                                                               ##STR35##     243-255 (265-266).sup.(+)                         24                                                                                   ##STR36##                                                                               ##STR37##     sirup                                             25                                                                                   ##STR38##                                                                               ##STR39##     oil                                               26                                                                                   ##STR40##                                                                               ##STR41##     oil                                               27                                                                                   ##STR42##                                                                               ##STR43##     sirup                                             28                                                                                   ##STR44##                                                                               ##STR45##     sirup                                             29                                                                                   ##STR46##                                                                               ##STR47##     113-119                                           30                                                                                   ##STR48##                                                                               ##STR49##     sirup                                             31                                                                                   ##STR50##                                                                               ##STR51##     semi- crystalline                                 32                                                                                   ##STR52##                                                                               ##STR53##     sirup                                             33                                                                                   ##STR54##                                                                               ##STR55##     sirup                                             34                                                                                   ##STR56##                                                                              O(CH.sub.2).sub.2 CH.sub.3                                                                    semi- crystalline                                 35                                                                                   ##STR57##                                                                              OCH(CH.sub.3).sub.2                                                                           oil                                               36                                                                                   ##STR58##                                                                              O(CH.sub.2).sub.3 CH.sub.3                                                                    semi- crystalline (100-104).sup.(+)               37                                                                                   ##STR59##                                                                              OC(CH.sub.3).sub.3                                                                            sirup                                             38                                                                                   ##STR60##                                                                               ##STR61##     104-122 (122-133).sup.(+)                         39                                                                                   ##STR62##                                                                               ##STR63##     sirup                                             40                                                                                   ##STR64##                                                                               ##STR65##     sirup                                             41                                                                                   ##STR66##                                                                               ##STR67##     semi- crystalline (163-164).sup.(+)               42                                                                                   ##STR68##                                                                               ##STR69##     sirup                                             43                                                                                   ##STR70##                                                                               ##STR71##     129-157                                           44                                                                                   ##STR72##                                                                               ##STR73##     sirup                                             45                                                                                   ##STR74##                                                                              OCH.sub.3      117-122                                           46                                                                                   ##STR75##                                                                              OC.sub.2 H.sub.5                                                                              semi- crystalline                                 47                                                                                   ##STR76##                                                                               ##STR77##     105-135                                           48                                                                                   ##STR78##                                                                              O(CH.sub.2).sub.3 CH.sub.3                                                                    sirup                                             49                                                                                   ##STR79##                                                                               ##STR80##     sirup                                             50                                                                                   ##STR81##                                                                               ##STR82##     sirup                                             51                                                                                   ##STR83##                                                                              N(CH.sub.2 CH.sub.2 CH.sub.3).sub.2                                                           117-120                                           52                                                                                   ##STR84##                                                                              O(CH.sub.2 ).sub.3 CH.sub.3                                                                   oil                                               53                                                                                   ##STR85##                                                                               ##STR86##     sirup                                             54                                                                                   ##STR87##                                                                              O(CH.sub.2).sub.4CH.sub.3                                                                     sirup                                             55                                                                                   ##STR88##                                                                              O(CH.sub.2).sub.5CH.sub.3                                                                     semicrystalline                                   56                                                                                   ##STR89##                                                                               ##STR90##     sirup                                             __________________________________________________________________________                                  n.sub.D.sup.30 (refractive index; not me-         Example                      asured with viscous sirupy                        No.  R.sub.1  R.sub.2        products)                                         __________________________________________________________________________     57                                                                                   ##STR91##                                                                               ##STR92##     1.5779                                            58                                                                                   ##STR93##                                                                               ##STR94##     1.5798                                            59                                                                                   ##STR95##                                                                               ##STR96##     1.5926                                            60                                                                                   ##STR97##                                                                               ##STR98##     1.5859                                            61                                                                                   ##STR99##                                                                               ##STR100##    1.5688                                            62                                                                                   ##STR101##                                                                              ##STR102##    1.5755                                            63                                                                                   ##STR103##                                                                              ##STR104##    1.5768                                            64                                                                                   ##STR105##                                                                              ##STR106##    1.5843                                            65                                                                                   ##STR107##                                                                              ##STR108##    1.5532                                            66                                                                                   ##STR109##                                                                             OCH(CH.sub.3).sub.2                                                                           1.5587                                            67                                                                                   ##STR110##                                                                              ##STR111##    1.5501                                            68                                                                                   ##STR112##                                                                             O(CH.sub.2).sub.2 CH.sub.3                                                                    1.5602                                            69                                                                                   ##STR113##                                                                             OCH(CH.sub.3).sub.2                                                                           1.5583                                            70                                                                                   ##STR114##                                                                             OCH.sub.2 CH(CH.sub.3).sub.2                                                                  1.5372                                            71                                                                                   ##STR115##                                                                             O(CH.sub.2).sub.2 CH.sub.3                                                                    1.5682                                            72                                                                                   ##STR116##                                                                              ##STR117##    1.5812                                            73                                                                                   ##STR118##                                                                              ##STR119##    1.5863                                            74                                                                                   ##STR120##                                                                              ##STR121##    sirup                                             75                                                                                   ##STR122##                                                                              ##STR123##    sirup                                             76                                                                                   ##STR124##                                                                              ##STR125##    sirup                                             77                                                                                   ##STR126##                                                                              ##STR127##    semicrystalline                                   78                                                                                   ##STR128##                                                                              ##STR129##    semicrystalline                                   79                                                                                   ##STR130##                                                                              ##STR131##    sirup                                             80                                                                                   ##STR132##                                                                              ##STR133##    1.5328                                            81                                                                                   ##STR134##                                                                              ##STR135##    sirup                                             82                                                                                   ##STR136##                                                                              ##STR137##    semicrystalline                                   83                                                                                   ##STR138##                                                                              ##STR139##    sirup                                             84                                                                                   ##STR140##                                                                              ##STR141##    sirup                                             85                                                                                   ##STR142##                                                                              ##STR143##    sirup                                             86                                                                                   ##STR144##                                                                             O(CH.sub.2).sub.7 CH.sub.3                                                                    semicrystalline                                   87                                                                                   ##STR145##                                                                             O(CH.sub.2).sub.2 OC.sub.2 H.sub.5                                                            sirup                                             88                                                                                   ##STR146##                                                                             O(CH.sub.2).sub.3 Cl                                                                          sirup                                             89                                                                                   ##STR147##                                                                              ##STR148##    1.5789                                            90                                                                                   ##STR149##                                                                              ##STR150##    semicrystalline                                   __________________________________________________________________________      .sup.(+) melting point of samples recrystallized from toluene/hexane     

(B) EXAMPLES OF FORMULATION

EXAMPLE A

A dusting powder is obtained by mixing

10 parts by weight of active substance and

90 parts by weight of talc as inert material and comminuting the mixture in a hammer mill.

EXAMPLE B

A wettable powder which is easily dispersible in water is obtained by mixing

25 parts by weight of active substance

64 parts by weight of quartz containing kaolin as inert material

10 parts by weight of potassium lignosulfonate and

1 part by weight of sodium oleoyl-methyl-tauride as wetting and dispersing agent and grinding the mixture in a pin mill.

EXAMPLE C

A dispersion concentrate readily dispersible in water is obtained by mixing

20 parts by weight of active substance

6 parts by weight of nonylphenol polyglycol ether (10 EO)

3 parts by weight of isotridecanol polyglycol ether (8 EO) and

71 parts by weight of paraffinic mineral oil (boiling range 255° to >377° C. at atmospheric pressure)

and grinding the mixture in a ball mill to a particle size below 5 microns.

EXAMPLE D

An emulsifiable concentrate is obtained from 15 parts by weight of active substance 75 parts by weight of cyclohexanone as solvent, and 10 parts by weight of oxethylated nonyl phenol (10 EO) as emulsifier.

(C) BIOLOGICAL EXAMPLES

EXAMPLE I

Wheat plants in the three-leaf stage were strongly infested with conidia of powdery mildew of cereals (Erysiphe graminis) and then kept in the greenhouse at 20° C. and a relative atmospheric humidity of 90 to 95%. 3 Days after infestation, the plants were sprayed to the drip off with spray liquors containing the compounds indicated in Table I in concentrations of 500, 250, 125, 60, 30 and 15 mg of active substance per liter. As comparative agent Maneb was used. After a time of incubation of 10 days, the plants were examined as to their degree of infestation with mildew, which is indicated in the table in % of infested leaf area with respect to untreated but infested control plants (100% infestation).

The results are indicated in Table I.

                  TABLE I                                                          ______________________________________                                                   leaf surface in percent infested with powdery                                  mildew after treatment with mg of active sub-                        Compound  stance per liter of spray liquor                                     of Ex. No.                                                                               500     250     125   60    30    15                                 ______________________________________                                         13        0       5       15    25                                             11        0       5       15    25                                              9        0       3-5     10    15                                             10        0       5       15    25                                             12        0-3     5       15    25                                             20        0-3     3       10    15                                             14        0-3     3        5    10                                             27        0       0       0      5    10-15                                     1        0       0       3-5   10     15                                       2        0       0       0     3-5    10                                      35        0       0       0     0     5                                        34        0       0       0     0     0-3   3-5                                37        O       0       0     0     3     5                                  81        0       0       0     0     3     5                                  89        0       0       0     0     3     5                                  80        0       0       0     0     0     0                                  78        0       0       0     0     0     0                                  75        0       0       0     0-3   5      15                                74        0       0       0     0     5      10                                73        0       0       0-3   15-10  15     25                               90        0       0       0     0     3     5                                  Maneb*    5       10      15    25                                             untreated infested plants  100                                                 ______________________________________                                          *Maneb = manganous ethylene bisdithiocarbamate                           

EXAMPLE II

Cucumber plants of the type Delikatess in the two-leaf stage were strongly infested with a conidia suspension of cucumber mildew (Erysiphe cichoracearum). The spore suspension was allowed to dry on the plants for 30 minutes, whereupon they were transferred to the greenhouse having a temperature of 22° C. and a relative humidity of 90%. 3 Days after infestation the plants were sprayed to the drip off with spray liquors of the compounds listed in Table II in the indicated concentrations. As comparative agent Maneb was used. The plants were inspected as to their degree of infestation 10 days after the treatment. The degree of infestation is expressed in % of infested leaf area, relative to untreated but infested control plants (100% infestation). The results are indicated in Table II.

                  TABLE II                                                         ______________________________________                                                  leaf surface in percent infested with cucumber                                 mildew after treatment with mg of active sub-                         Compound stance per liter of spray liquor                                      of Ex. No.                                                                              500     250     125    60    15     8                                 ______________________________________                                         13       0       3-5     10     15                                             11       0       3-5     5-10   15                                              9       0       3-5     10     15-25                                          10       0       3-5     15     25                                             12       0        3       3      5-10                                          20       0-3      5      10     15                                             14       0       0-3      5     10-15                                          25       0       0-3      5     10-15                                          27       0       0       0      0-3    5-10                                     1       0       0       0      0     0-3                                       2       0       0       0      0     3                                        35       0       0       0      0     0      5                                 90       0       0       0      0     3                                        81       0       0       0      0     3                                        89       0       0       0      0     3                                        80       0       0       0      0     0                                        78       0       0       0      0     0                                        75       0       0       0      0     0-3                                      74       0       0       0      0     0-3                                      73       0       0       0      0     0-3                                      Maneb*    15     25      35     60     100                                     untreated infested plants  100                                                 ______________________________________                                          *Maneb = manganous ethylene bisdithiocarbamate                           

EXAMPLE III

Cucumber plants of the type Delikatess in the two-leaf stage were strongly infested with a conidia suspension of Benomyl-resistant cucumber mildew (Erysiphe cichoracearum). The spore suspension was allowed to dry on the plants for 30 minutes, whereupon they were transferred to the greenhouse having a temperature of 22° C. and a relative humidity of 90%. 3 Days after infestation the plants were sprayed to the drip off with spray liquors of the compounds listed in Table III in the indicated concentrations. As comparative agent Maneb was used. The plants were inspected as to their degree of infestation 10 days after the treatment. The degree of infestation is expressed in % of infested leaf area, relative to untreated but infested control plants (100% infestation). The results are indicated in Table III.

                  TABLE III                                                        ______________________________________                                                  leaf area infested with cucumber mildew                                        (strain resistant to Benomyl) in % with mg of                         Compound active substance per liter of spray liquor                            of Ex. No.                                                                              500    250     125   60     15    7                                   ______________________________________                                         13       0      3-5     10    15                                               11       0      5        5-10 15                                                9       0      5       10    15                                               10       0      3-5     15    25                                               12       0      0       0-3   15-25                                            20       0      0-3     3-5   15                                               14       0      3        5-10 15                                               25       0      0       3-5   5-10                                             27       0      0        0     3     5      10                                  1       0      0        0    0      3-5   5                                    2       0      0        0    0      3-5   5                                   35       0      0        0    0      0     3                                   90       0      0        0    0      3-5                                       81       0      0       0     0      3                                         89       0      0       0     0      3                                         80       0      0       0     0      0                                         78       0      0       0     0      0-3                                       75       0      0       0     0      3-5                                       74       0      0       0     0      3-5                                       73       0      0       0     0      3                                         Maneb*    15     25     35    60      100   100                                untreated infested plants  100                                                 ______________________________________                                          *Maneb = manganous ethylene bisdithiocarbamate                           

EXAMPLE IV

Barley plants in the three-leaf stage were strongly infested with conidia of powdery mildew of cereals (Erysiphe graminis sp. hordei) and kept in the greenhouse at 20° C. and a relative humidity of 90 to 95%. Three days after infestation the plants were sprayed to the drip off with spray liquors of the compounds listed in Table IV in concentrations of 500, 250, 125, 60 and 30 mg per liter of spray liquor. Maneb was used for comparison. After a time of incubation of 10 days, the plants were examined as to the degree of infestation with mildew. The degree of infestation is expressed in percent of infested leaf area relative to untreated but infested control plants (100% infestation). The results are summarized in Table IV.

                  TABLE IV                                                         ______________________________________                                                   leaf surface in percent infested with powdery                                  mildew after treatment with mg of active sub-                        Compound  stance per liter of spray liquor                                     of Ex. No.                                                                               500     250      125    60     30                                    ______________________________________                                         13        0        5-10    15     25                                           11        0        3        5-10  15                                            9        0       3-5      10     25                                           10        0        3       10-15  25                                            8        0-3     10       15     25                                           12        0        5-10    15     25                                           20        0-3      5-10    15     25                                           14        0        5-10    15     25                                           25        0-3     10-15    25     35                                           27        0       0        0      3-5     10                                    1        0       0        0      0      3-5                                    2        0       0        0      0      3-5                                   35        0       0         3     3-5    5                                     34        0       0        0-3     5-10   15                                   37        0       0-3      3-5    10     15-25                                 90        0       0        0      0      3                                     81        0       0        0      0      0-3                                   89        0       0        0      0      3-5                                   80        0       0        0      0      0                                     78        0       0        0      0      0                                     75        0       0        0      0-3    5                                     74        0       0        0      0-3    3-5                                   73        0       0        0      0-3    3                                     Maneb*     25     35       60      100    100                                  untreated infested plants  100                                                 ______________________________________                                          *Maneb = manganous ethylene bisdithiocarbamate                           

EXAMPLE V

Apple stocks of the type EM IX in the four-leaf stage were strongly infested with a conidia suspension of powdery mildew of apple (Podosphaera leucotricha). The plants were cept for 16 hours in a climatic chamber having a temperature of 20° C. and a relative humidity of about 100% and then transferred to the greenhouse where the temperature was 22° C. and the relative humidity amounted to 85%. Three days after infestation the plants were sprayed to the drip off with the compounds listed in Table V in the indicated concentrations. Maneb was used for comparison. After 2 to 3 weeks the plants were inspected as to the degree of infestation with mildew, which is expressed in the table in % of infested leaf surface, relative to untreated but infested control plants (=100%). The results are summarized in Table V.

                  TABLE V                                                          ______________________________________                                                    leaf surface infested with apple mildew                                        in % with mg of active substance per liter                          Compound   of spray liquor                                                     of Ex. No. 1000     500      250     125                                       ______________________________________                                         12         0        0-3      5       15                                        14         0        0-3      5       25                                        27         0-3      3        5       15                                         1         0-3      3         5-10   15-25                                      2         0        0-3      3-5      5                                        35         0        0-3      5        5                                        Maneb*     25        35       60      100                                      untreated infested plants  100                                                 ______________________________________                                          *Maneb = manganous ethylene bisdithiocarbamate                           

EXAMPLE VI (growth inhibition)

In tray tests in the greenhouse young plants of cereals (wheat, barley and rye) in the three-leaf stage were sprayed to the drip off with spray liquors of the compounds listed in Table VI in the indicated concentrations (kg/hectare). 2-Chloroethyltrimethylammonium chloride, maleic acid hydrazide and succinic acid 2,2-dimethylhydrazide were used for comparison. When the untreated control plants had reached a height of growth of about 55 cm, the growth of all plants was measured and the inhibition was calculated in percent of the growth of the control plants. In addition, the phytotoxic effect of the compounds was examined. The results are indicated in Table VI, in which an inhibition of growth of 100% means no growth at all while 0% inhibition corresponds to the growth of the untreated control plants.

                                      TABLE VI                                     __________________________________________________________________________     Inhibition of growth in cereals                                                             concentra-                                                                     tion of                                                                        of active                                                         Compound     substance                                                                            % inhitition of growth                                                                    phytotoxic                                       of Ex. No.   kg/ha wheat                                                                              barley                                                                             rye                                                                               effect                                           __________________________________________________________________________     127          2.5   33  29  26 no damage                                                     1.25  30  28  10                                                  comparison   2.5   27  8   10 no damage                                        (2-chloroethyl)-trimethyl-                                                                  1.25  23  0    0                                                  ammonium chloride                                                              comparison   2.5   37  35  38 heavy damage                                     maleic acid hydrazide                                                                       1.25  20  20  29                                                  comparison   2.5    0  0    0 no damage                                        succinic acid 2,2-dimethyl-                                                                 1.25   0  0    0                                                  hydrazide                                                                      __________________________________________________________________________ 

What is claimed is:
 1. A 1,2,4-triazole derivative of the formula I ##STR151## in which R₁ denotes methyl or phenyl optionally substituted by halogen, (C₁ -C₄)alkyl or (C₁ -C₄)-alkoxy, andR₂ denotes the group R₃ O-- in which R₃ is alkyl, having up to 12 carbon atoms, which may be substituted additionally by halogen, (C₁ -C₄)alkoxy or alkoxycarbonyl having up to 8 carbon atoms; or is alkinyl having up to 3 carbon atoms; or is cycloalkyl having up to 6 carbon atoms and optionally substituted additionally by (C₁ -C₄)alkyl; or is phenyl optionally substituted by halogen or F₃ C--, or R₂ denotes ##STR152## in which R₄ is hydrogen or (C₁ -C₄)-alkyl optionally substituted by alkoxycarbonyl having up to 8 carbon atoms, and R₅ is (C₁ -C₄)alkyl or phenyl optionally substituted by halogen, F₃ C--, (C₁ -C₄)alkyl, (C₁ -C₄)alkoxy, phenoxy or halophenoxy.
 2. A pesticidal composition having fungicidal activity comprising a carrier or suitable auxiliary and as an active ingredient a compound as defined in claim
 1. 3. The composition of claim 2 wherein said compound is present in an amount of from 2 to 95% by weight of said composition.
 4. A pesticidal composition having plant growth regulating activity comprising a carrier or suitable auxiliary and as an active ingredient a compound defined in claim
 1. 5. The composition of claim 4 wherein said compound is present in an amount of from 2 to 95% by weight of said composition.
 6. A method of controlling plant infestation which comprises treating said plants with a compound as defined in claim
 1. 7. A method of regulating plant growth which comprises treating said plants with a compound as defined in claim
 1. 8. A method of inhibiting growth in cereals which comprises treating said cereals with a compound as defined in claim
 1. 